Figure 1.

MSC Niche in the Mouse Incisor

(A and B) To label fast-cycling cells (TACs), postnatal day 5 pups were given a single EdU injection (3.3 μg/g BW) and sacrificed after 16–24 hr (A). To identify slow-cycling cells, postnatal day 5 pups were given daily EdU injections (3.3 μg/g BW) for 4 weeks and traced for 2–6 months before tissue collection (B). Click-it EdU image kit was used for EdU detection on sagittal sections of mouse incisors. EdU was labeled with Alexa Fluor 594 dye and DAPI was used for nuclear labeling.

(C–G) Immunofluorescence showed that Ring1b (C) co-localized with EdU-labeled TACs (D) in dental mesenchyme (82% EdU⁺ are Ring1b⁺, and 70% Ring1b⁺ are EdU⁺). DAPi staining (E), merged image (F), and (G) Enlarged field of (F) showing localization of Ring1b and EdU⁺ in the TAC region.

(H–K) Immunolocalization of Ring1b (H) and slow-cycling (label-retaining) cells (I).

(J) Merged image.

(K) Tilescan image of (J).

(L) Loss of Ring1a/b showed decreased cell proliferation identified by Ki67 staining.

N ≥ 3 mice per group.